Yo, from what i know, u can have muscle fatigue/pain on some reasons like:

-There is then, the DOMS(Delayed Onset Muscle Soreness) theory , when you workout, muscles suffer some microruptures into its fibers, and the pain comes, when it isnt recovered at all.

-So you can get the lactic acid hypothesis...where acid lactic sets on the muscle and if you dont spread it over your body(by doing more exercise-like running, or light anaerobical ones), it sets on the sore muscle, make the fatigue/pain feeling show up.

Yo, from what i know, u can have muscle fatigue/pain on some reasons like:

-There is then, the DOMS(Delayed Onset Muscle Soreness) theory , when you workout, muscles suffer some microruptures into its fibers, and the pain comes, when it isnt recovered at all.

-So you can get the lactic acid hypothesis...where acid lactic sets on the muscle and if you dont spread it over your body(by doing more exercise-like running, or light anaerobical ones), it sets on the sore muscle, make the fatigue/pain feeling show up.

Ps:Lactic acid is a co-product from anaerobical glycosis(synthesis).Peace.

isnt lactic acid build by training failure and less time rest between set due to lack of oxygen? i alway avoid failure and rest 3 min to avoid lactic acid. but still sore, thanks your reply...

isnt lactic acid build by training failure and less time rest between set due to lack of oxygen? i alway avoid failure and rest 3 min to avoid lactic acid. but still sore, thanks your reply...

Lactic acid is the third energy system that the human body goes through. The first is the Adenasine Triphosphate which is usually paired up with the second, the phosphocreatine stage. Lactic acid comes from the anaerobic glycosis system which breaks down glucose into usable energy. Lactic acid is the same acid that is present in sour milk. Lactic acid generally builds up in about 60-120 seconds of work (at least, that's from the studies I've read). I don't think there's a good reason to avoid lactic acid, because using that system will just make it more efficient and less likely for lactic acid to be as big of a deal later on in your training, At least, that's my take.

Its all about intensity. If an exercise is intense and you can perform only 3 - 5 reps then you are working strength. In this case you are experiencing DOMS and micro tears of the muscles from overload. If you are working high rep numbers ie +15 then it is lactic/endurance training. Easy

As for rest times I try to go by how I feel physically and mentally. For example if I feel ready I will perform the set/exercise, I find this keeps me in the zone much more than waiting around more time than I need to.